This is a tough one. I was spanked, not beaten, as a child. I deserved probably every one I got, and I can remember maybe 3 of them. So I am not emotionally scarred from them, but here is something to think about.

I am sure I received more than three in my life, but if the first one or even second one didn't stop my negative behavior, then was it that effective? I think taking away my tv time, outside time or something I enjoyed was much more traumatic for me and gave me a "want" to do better. I know you say she throws fits til she gets her way, but if you don't give in, just put her in her room and let her throw the fit, she'll eventually wear out and realize, this isn't working for me and I still don't have that favorite toy, or can't go to my friends party or whatever was taken away.

In the long run, that is more align with how the real world works. If you mess up in your job, chances are you are not going to get a physical punishment, but something more tangible. Warnings, possible pay adjustment, reassigned to a different, less desirable position, etc. to remedy the actions.

Side note.... Warnings only work if the punishment follows further negative behavior. I would suggest researching behavior techniques that have worked for others and sit down with your wife to make a plan and you both stick to. That's the only way any correction in behavior will work. Not random threats one day, giving in another and throwing in a spanking here and there. It's too confusing to the child. They gamble on the chance of you giving in or doing nothing.